SStolen

iTrader: (22)

Like the title says: I wanted to know how much rwhp that can be had using the stock feed line as the feed line and the evap line as the return. I will be upgrading the rails and lines up front with -6an line.

Looking for 800rwhp if possible.

There was a guy locally that I know made 640 on a mustang so that is easily 700rwhp on a dynojet. And it doesn't sound true but I could have sworn he did it on 93 pump, stock fuel rails, and NO meth. I'm almost positive that all he had was Mototron 60# injectors, a casper voltage booster, and a SINGLE Walbro in-tank but that can't be right. I'm gonna have to investigate.

sloganish

iTrader: (1)

if your seeking 800whp, you shouldnt spare the cash to run a custome fuel system. when you reach higher hp like that theres no reason to cheap out, any 800rwhp motor will be sucking fuel like a bad bitch!

ChevyChad

iTrader: (50)

Well, I'm making 632 with mine w/o meth, and I have plenty of fuel. I've got dual intank pumps and 60# injectors tho. I've heard the factory hard lines are good to 750rwhp from someone who has done it before.

qqwqeqwrqwqtq

We've made 995rwhp with stock feed/evap return through a turbo400 and twin external walbros, and 1,150rwhp with stock feed/evap return through a 6-speed with an intank walbro and external bosch "Y'd" together.

the_merv

iTrader: (88)

^^There's the winner..that's alot of power..

6techniques

iTrader: (7)

And how was the fuel readings? Any signs of starvation? Was this on a FI setup, and if so how many cid and how much psi? And lastly, did you guys do it as a test or is this how the car stayed hooked up? Im curious as to why there are so many people who think that the lines need to be upgraded when numbers like that can be acheived on the stock ones.

qqwqeqwrqwqtq

Fuel pressure was staying steady at base+boost (as in 1-1 referenced). No drop of pressure at all.

First car was 370ci single turbo, second car was 408ci twin turbo, both were around 23psi boost. The cars left the shop that way, the automatic being together for a few years now and the 6-speed leaving just recently.

The stock feed line has so far never shown itself to be a problem so we usually don't have a reason to change it.

6techniques

iTrader: (7)

Thats music to my ears!

Sending you a PM thanks

SStolen

iTrader: (22)

Music to my ears as well! I was just now thinking that I might want to push it to 850rwhp at some point so I might as well just change the feed line even though I will probably never go past 700. ... I'm a *****.

1. I have a single Walbro now and was going to do a second in-tank walbro (I usually fill it up at half tank anyways). Is it recommended to wire them up so that they both run all of the time or is a Hobbs switch on the second pump reliable? I'm assumming their must be a down-side to wiring the pumps so that they are both always on or else more people would do it.

2. Am I okay to run -6an line to my fuel rails or should I run -8? The factory feed line is no bigger than -6an anyway right, so that shouldn't be the main restriction?

3. I saw a few different write-ups and people seem to use bulkhead fittings in the factory bucket to connect the twin in-tank pumps. They're usually using a new feed line altogether though. Can I use the factory bucket feed connection coming out of the bucket or do I need to install a larger bulkhead fitting and run a short line to the factory T-fitting where the factory return is?

4. I know I need to remove the in-tank FPR and plug the 'T' for the factory return. Anyone know what size NPT fitting that is?

Thanks.

ChevyChad

iTrader: (50)

1) You don't need the extra fuel pressure when you are not in boost- no point having them both run at the same time all the time. Use a boost switch like a Hobbs (I got mine off ebay for like $11- not a Hobbs, but a boost switch is a boost switch it aint rocket science )

2) If you are going to use the factory feed line, it is 3/8 which is the same as a -6, so you wouldn't be doing anything at all by going to a -8 from a 3/8 line. (-8 is 1/2)

3) I used a 'Y' for my intank pumps and just have one single line going out the factory feed from the bucket. No bulkhead fittings at all on mine.

4) I am pretty sure the factory T is a 1/8" NPT pipe plug fitting you will need.

BlkHwk

iTrader: (8)

You would or could be gaining by having less pressure drop through the line from the tank to the rails.

ChevyChad

iTrader: (50)

True, if you replace the entire line from the tank to the rails. I was talking about using the stock hard line (which is 3/8) and then using -8 (1/2) line after that from the 3/8 hard line to the rails. No point in doing that. If you did do a -8 feed line coming from the tank, you would have to use a bulkhead fitting...

trtturbo

iTrader: (25)

We did the dual intank set up with bulkhead fittings. This is for a Hummer with a 408 and turbo. The factory non return set up has a very small opening in the feed right out of the sending unit.
It may be a little overkill, but we are using two feed lines, one to each rail and the old evap line for the return.

No Juice

iTrader: (11)

The factory T is a 1/4" NPT not 1/8"

ChevyChad

iTrader: (50)

OK thanks for the correction.

BlkHwk

iTrader: (8)

I'm pretty sure I am gonna try just using the stock lines but I would think if you wanted you could find a way to adapt from the 3/8" quick connect @ the tank to -8 to run from the tank to rails.

BlkHwk

iTrader: (8)

O.K. someone please answer me this question. What is the big deal with using the evap for return? I have heard it is ideal to have the reg. after the rails. But Y not just replace the factory T in the feed line and mount the reg. there and run the return off the reg. back to tank? Fluid doesn't compress, I would think the pressure should be the same there as it would @ the rails. Pretty sure that's why GM did it that way. How much difference does it really make? I would think little to none as long as you have plenty of volume feeding the rails.

ChevyChad

iTrader: (50)

Yes you could... And they actually make a fitting that does exactly that.

Jeg's p/n 027-15118 $36.99

It is a 3/8" quick connect to a -8AN fitting.



I don't think it will flow anymore than a -6AN tho since the line feeding it is a -6 size.

You will have a pressure drop across the rails. Placing the regulator after the rails ensures you have the same pressure at every injector on the rails. And replacing the Tee with a FPR has been done before. I'd say do a search, but I doubt today is the day of this month the search function is working

BlkHwk

iTrader: (8)

Thanks for the info on the fitting Chad. I wouldn't think the flow would be decreased, just the velocity of the fuel coming out of the -6 quick coupler would be increased until it hits the -8. After all the outlet of the pump is pretty small. Benefit would be less pressure drop after the tank. I would like to search this. I am interested in reading more about installing the reg. where the T is. I've been considering doing mine like this. I see what your saying about a pressure drop @ the rails due to the inj. My gauge is installed @ the rails now. I might try it and see what it does.

qqwqeqwrqwqtq

The regulator mounted at the factory 'T' will not allow the regulator to compensate for pressure drop across the line so it will not work correctly.